Z.Djurcic, D.Leonard, A.Piepke Physics Dept, University of Alabama, Tuscaloosa AL P.Vogel
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Transcript of Z.Djurcic, D.Leonard, A.Piepke Physics Dept, University of Alabama, Tuscaloosa AL P.Vogel
Z.Djurcic, D.Leonard, A.Piepke Physics Dept, University of Alabama, Tuscaloosa AL
P.Vogel Physics Dept Caltech, Pasadena CA
A. Bellerive, M. Dixit, C. Hargrove, D. Sinclair Carleton University, Ottawa, CanadaW.Fairbank Jr., S.Jeng, K.Hall
Colorado State University, Fort Collins COM.Moe
Physics Dept UC Irvine, Irvine CAD.Akimov, A.Burenkov, M.Danilov, A.Dolgolenko, A.Kovalenko, D.Kovalenko, G.Smirnov, V.Stekhanov
ITEP Moscow, RussiaJ. Farine, D. Hallman, C. Virtue
Laurentian University, CanadaM.Hauger, L.Ounalli, D.Schenker, J-L.Vuilleumier, J-M.Vuilleumier, P.Weber
Physics Dept University of Neuchatel, Neuchatel SwitzerlandM.Breidenbach, R.Conley, C.Hall, A.Odian, C.Prescott, P.Rowson, J.Sevilla, K.Skarpaas, K.Wamba,
SLAC, Menlo Park CAE.Conti, R.DeVoe, G.Gratta, M.Green, T.Koffas, R.Leon, F.LePort, R.Neilson, S.Waldman, J.Wodin
Physics Dept Stanford University, Stanford CA
EEnriched nriched XXenon enon OObservatorybservatoryfor double beta decayfor double beta decay
Double Beta Decay
-
-
1 2 2) : ( , ) ( , ) A Z A Z e e ec
ec
T G E Z MGT1 22 1 2
02 2
/ ,
2
20
2
20
00
102/1
,
mMg
gMZEG
T
FA
VGT
d(n) u(p)
ece
e
W
W
d(n) u(p)
ce
L0
2 0 2) : ( , ) ( , ) A Z A Z e e
e-c
eRW
d(n)
d(n)
u(p)
u(p)
W e-eL
m
N
i
Lej
Lejj UUmm
2
1
L 2
Eee
dN dt
E0
(A,Z)
0+ (A,Z+1)
(A,Z+2)
2+
0+
E0e-e-
Popular candidates
E0 (MeV) Abundance (%)
0.187 4.27148Ca 48Ca76Ge 76Ge 2.040 7.8 82Se 82Kr 2.995 9.2
100Mo 100Ru 3.034 9.6128Te 128Xe 0.868 31.4130Te 130Xe 2.533 34.5136Xe 136Ba 2.479 8.9150Nd 150Sm 3.367 5.6
232Th 232U 238U 238Pu
0.858 1001.145 99.3
dirdirdir, geodirdir, geodir, geodir
melking
dir
Isotopic enrichment for a gaseous substance like Xe is Isotopic enrichment for a gaseous substance like Xe is most economically achieved by ultracentrifugationmost economically achieved by ultracentrifugation
This separation step thatThis separation step thatrejects the light fractionrejects the light fractionis also very effective inis also very effective in
removing removing 8585Kr (TKr (T1/21/2=10.7 yr)=10.7 yr)that is present in the that is present in the
atmosphere from spentatmosphere from spentfuel reprocessingfuel reprocessing
Russia has enoughRussia has enoughproduction production
capacitycapacityto process 100 ton to process 100 ton
Xe and extract Xe and extract up to 10 ton up to 10 ton 136136Xe Xe
in a finite timein a finite time
Nucleus QRPA
Caltech
Shell model
Strasbourg-Madrid
exp
48Ca - 0.91 4.3 x 1019
76Ge 0.71 1.44 1.8 x 1021
82Se 1.5 0.46 8.0 x 1019
100Mo 0.6 - 1.0 x 1019
130Te 0.33 0.35 6.6 x 1020
128Te 0.27 0.25 2.0 X 1024
130Te 0.27 0.29 8.0 x 1020
136Xe <1.0 <2.6 >8.1 x 1020
pex
calc
T
T
2/1
2/1 )(22/1 yrT
pex
calc
T
T
2/1
2/1
direct
direct
geochem.
Enriched Xenon Observatory
for double beta decayAlabama, Caltech, Carleton, Colorado, UC Irvine, ITEP Moscow, Laurentian, Neuchatel, SLAC, Stanford
Ba+Ba+
system best studied (Neuhauser, system best studied (Neuhauser, Hohenstatt, Toshek, Dehmelt 1980)Hohenstatt, Toshek, Dehmelt 1980)Very specific signature “shelving” Very specific signature “shelving” Single ions can be detected from a Single ions can be detected from a photon rate of 10photon rate of 1077/s/s
22PP1/21/2
44DD3/23/2
22SS1/21/2
493nm493nm650nm650nm
metastable 47smetastable 47s
Much improved signature!
136136Xe: Xe: 136136Ba++ e- e- final state can be tagged usingBa++ e- e- final state can be tagged using optical spectroscopy optical spectroscopy (M.Moe PRC44 (1991) 931)(M.Moe PRC44 (1991) 931)
Two detector options under considerationTwo detector options under consideration
High Pressure gas TPCHigh Pressure gas TPC• 5-10 atm, 50 m5-10 atm, 50 m33 modules, modules, 10 modules for 10 t10 modules for 10 t•Xe enclosed in a non-Xe enclosed in a non-structural bagstructural bag• range ~5-10cm: range ~5-10cm: can resolve 2 blobscan resolve 2 blobs•2.5m e-drift at ~250kV2.5m e-drift at ~250kV•Readout Xe scintillation withReadout Xe scintillation with WLSB (T0)WLSB (T0)•Additive gas: quenching and Additive gas: quenching and BaBa++ ++ BaBa+ + neutralizationneutralization•Steer lasers or drift Ba-ion to Steer lasers or drift Ba-ion to detection regiondetection region
Liquid Xe chamberLiquid Xe chamber•Very small detector (3mVery small detector (3m33 for for 10tons)10tons)•Need good E resolutionNeed good E resolution•Position info but blobs not Position info but blobs not resolvedresolved•Readout Xe scintillationReadout Xe scintillation•Can extract Ba from hi-density Can extract Ba from hi-density XeXe•Spectroscopy at low pressure:Spectroscopy at low pressure: 136136Ba (7.8% nat’l) different Ba (7.8% nat’l) different signature from natural Ba signature from natural Ba (71.7% (71.7% 138138Ba)Ba)•No quencher needed, No quencher needed, neutralization neutralization done outside the Xedone outside the Xe
e-, 232Th
(E)/E=3.4 % at 1.59 MeV
(E)/E= 2.7 % at 2.48 MeV
Gotthard 5 bar xenon
(from cathode), 210Po (238U chain)
quenching (/e-)=1/6.5
(E)/E=1.1 % at 2.48 MeV !
Energy resolution
/EF(E/W)E)/E(
F=0.19, W=22 eV
(E)/E=0.13 % at 2.48 MeV !
Light detection (electroluminescence)in xenon (+CF4?)
Doped fibers : 1 step WLS UV (180 +/-20nm) to blue or 2 step WLS with coated fibers
e- track
Optical fibers x-y
Multianode photomultiplier
Grid (metallic cloth)
UV photons
Anode (charge)
Two gap scheme:Grid (metallic cloth)
anode
ITEP-Moscow, Kharkov, Neuchâtel
Fibers (250 m)
1 kV/cm
Found a clear (anti)correlation between ionization and scintillationFound a clear (anti)correlation between ionization and scintillation
~570 keV~570 keV
Major effort now: liquid xenon
Have demonstrated that we can get sufficient energyHave demonstrated that we can get sufficient energyresolution in LXe to separate the 2resolution in LXe to separate the 2νν from the 0from the 0νν modesmodes
We can do ionization measurements
as well as anyone
Now we turn on our newcorrelation technique…
Resolu
tions
Resolu
tions
at 5
70 keV
at 5
70 keV
3.3%@570keV3.3%@570keVor 1.6%@2.5MeVor 1.6%@2.5MeV
Initial Ra/Th ionInitial Ra/Th iongrabbing successfulgrabbing successful
As expected release from aAs expected release from afinite size metallic tip finite size metallic tip
is challengingis challenging
214214Po (164ms)Po (164ms)
230230U (20.8d)U (20.8d)
222222Ra (38s)Ra (38s)
210210Pb (22yr)Pb (22yr)
226226Th (30.5min)Th (30.5min)
218218Rn (35ms)Rn (35ms)
5.99MeV5.99MeV
6.45MeV6.45MeV
6.68MeV6.68MeV
7.26MeV7.26MeV
7.83MeV7.83MeV
αα
230230U source U source αα spectrum spectrumas delivered by LLNLas delivered by LLNL
and measured in vacuumand measured in vacuum
αα spectrum fromspectrum fromwhatever is grabbedwhatever is grabbed
by the tipby the tip(in Xe atmosphere)(in Xe atmosphere)
αα
αα
αα
αα
Ion Trap R&D at UHV/atmospheric pressure
RF quadrupole trap RF quadrupole trap loaded in UHV from loaded in UHV from
a Ba dispensera Ba dispenserand e-beam ionizerand e-beam ionizer
Xe can be injected Xe can be injected while observing while observing
the ionsthe ions
Indeed we are talking about single ions: one can load the trapIndeed we are talking about single ions: one can load the trapwith multiple ions and then observe the signal intensity as ionswith multiple ions and then observe the signal intensity as ions
are dropped one by one…are dropped one by one…
Zero ion backgroundZero ion background
All above in UHV;Perform the sameexperiment in noblegas atmosphere
In parallel, build liquid TPC prototype, without Ba tagging
• Prototype Scale:– 200 Kg enriched 136Xe– All functionality of EXO except Ba identification– Operate in WIPP for ~two years
• Prototype Goals:– Test all technical aspects of EXO (except Ba id)– Measure 2 mode– Set decent limit for 0 mode (probe Heidelberg-
Moscow)
Massive materials qualification programled by Alabama with contributions from
Carleton, Laurentian and Neuchatel
•Approximate detector simulation with material properties to establish target activities•NAA whenever possible (MIT reactor + Alabama)•Direct Ge counting at Neuchatel, Alabama and soon Canada•High sensitivity mass spectroscopy starting in Canada•Alpha counting at Carleton and Stanford•Rn outgassing measurements starter at Laurentian (Xe plumbing)•Full detector simulation in progress
APD plane below crossed wire array
100 APD channels (7 APD grouped together) provide light and t0
200 ionization channels (groups of wires 100 x +100 y)
Can define fiducial volume
Cryostat Cross Section
Condenser
Xenon Heater
should be
on this area
Xenon
Chamber
Outer Copper Vessel
Inner Copper Vessel
FC-87
FC-87
1” thick Thermal Insulation (MLI-vacuum), not shown to scale
Outer Door
Inner Door
Xenon
Chamber
Support
Status
• Enriched Xe in hand.
• Clean room installed at Stanford.
• WIPP agreement, including Environmental Impact, complete.
• Cryostat being designed.
• Xe purification and refrigeration issues being finalized
• Detector vessel, readout, and electronics being engineered.
200 kg prototype, estimated sensitivity, without Ba tagging
Estimate background from radioactivity (2 negligible)
Mass
(kg)
Enrichment
(%)
Eff.
(%)
(%)
Time
(yr)
Background
(events)
T1/20
(yr)
<m>(eV)
RQRPA
200 80 70 1.6 2 40 6.4*1025 0.28
V. A. Rodin et al. Phys.Rev. C68 (2003) 044302
Ultimate sensitivity, assuming
1) that the Xe chamber + Ba tagging gives 0 background from radioactivity...2) that the energy resolution is (E)/E=2 % (2background!)
Conclusion:
With a coordinated effort, the meV region is within reach!
Mass
(kg)
Enrichment
(%)
Eff.
(%)
(%)
Time
(yr)
Background
(events)
T1/20
(yr)
<m>(eV)
RQRPA
1000
10000
80
80
70
70
1.6
1.0
5
10
0.5 (use 1)
0.7 (use 1)
2.0*1027
4.1*1028
0.05
0.01